Cement: This is the binder used to join other materials.
Aggregates: coarse aggregates (greater than 3/8 "in diameter) and fine aggregates (sand).
Water: Water is the most important element in the quality of concrete manufacturing and is necessary for two purposes:
Hydration to create a chemical reaction with cement.
To help workability (water/cement ratio).
Admixtures: are ingredients other than cement, water, and aggregates that are added to the mixture just before or during mixing. Examples include chemical retardants, accelerators, water reducers, and superplasticizers; mineral fly ash, silica smoke, and slag.